This invention relates the field of marking materials using lasers. More specifically, this invention relates to the field of marking materials using laser vitrification techniques.
The widespread usage of bricks as building materials on highly visible areas such as walkways and building fronts has led artisans to attempt to decorate or mark bricks with letters or graphical patterns. As such, the laser marking of brick, pavers, terra-cotta tiles, and other high clay content materials is known in the art.
Currently, surface coating techniques utilize marking mediums, which include either a glass frit containing an energy absorbing enhancer, or a mixed metal oxide or a mixed organic pigment. Using current methods, the marking medium is placed in physical contact with the brick, or other substrate, and the medium is irradiated using a low-energy laser. The irradiation causes the marking material to solidify, and a raised, marking layer is formed on the top surface of the substrate. The non-irradiated portion of the marking material is then removed from the substrate.
Using surface-marking methods, the substrate is not damaged. A raised marking layer is formed on the surface of the substrate. This raised marking layer is thereby subject to damage from cracking due to wear, impacts, thermal stresses and the like.
Therefore, a permanent marking technique is needed that produces a marking that is not susceptible to damage from cracking due to wear, impacts, thermal stresses and the like.